Two-way stretch fabric and method for the preparation thereof

ABSTRACT

A lengthwise and crosswise stretchable fabric comprising bicomponent polyester filaments produced by conjugate spinning in side-by-side relationship component (A), a polyethylene terephthalate copolymerized with a structural unit having a metal sulfonate group, and component (B), a polyethylene terephthalate or polybutylene terephthalate. The fabric is rendered stretchable by inducting crimps in the bicomponent filaments thereof through exposure to infrared rays while said filaments are in a relaxed condition. The filaments may have been mechanically crimped prior to being formed into the fabric.

TECHNICAL FIELD

The present invention relates to a stretch fabric prepared by using aconjugate fiber and a method for the preparation thereof.

BACKGROUND OF THE INVENTION

A two-way stretch fabric prepared by polyurethane elastic fibers hasbeen known. However, the fabric has problems in heat resistance, lightresistance, chemical resistance, dyeing property and fungus resistanceas disadvantages of the polyurethane material. Further, since thestretching property is based on a rubber-like elasticity, its stretchingrate reaches to as high a value as not lower than 400%, but a stressvalue for the stretching rate when the stretching property is practicalin use is rather high and thus it gives a tight clamp of rubber-likeelasticity which limits its application.

Further, in order to obtain a two-way stretch non-woven fabric, anon-woven fabric of loose tissue with little enveloping of the fibercoated with a natural rubber latex also is known. However, the non-wovenfabric has a low stretching rate lower than 9% and has a disadvantage offorming texture slipage in use and of being broken.

Additionally, a non-woven fabric prepared by a procedure in which acrimping treatment is applied on polyamide fibers, and webs are formedusing them, and then they are resin-treated, is known. However, thestretching is limited to the lateral direction and the stretching rateis also as low as lower than 9%.

Japanese Laid-Open Patent Publication No. 168159 of 1974 disclosesnon-woven fabrics having a high elastic recovery and a soft feeling,which are prepared by point-bonding with a fibrous polymer (C) having alow melting point a web comprising an eccentric sheath & core conjugatefiber produced with two components, 5-sulfo-isophthalic acidcopolymerized polyester (A) and polybutyrene terephthalate (B).

On the other hand, side by side conjugate fibers have been used toproduce wadding, raw stock for quilting and the like, woven fabrics,knitted fabrics, bulky yarns for handcraft, non-woven fabrics and thelike. For example, Japanese Laid-Open Patent Publication No. 80561 of1980 discloses raw stock for wadding prepared with conjugate fibers inwhich differences of sulfonic acid group comprised in the polymer are atleast 0.4 mol % and low angle scattering strength of X-rays is less than15, and further discloses in the examples acrylic conjugate fiberproduced by a side by side method in which differences of sulfonic acidgroup are 0.2 to 1.5 mol %. Japanese Laid-Open Patent Publication No.70012 of 1986 discloses polyester conjugate fibers having a specificheat shrinkage which are produced by eccentrically bonding polyester (A)copolymerized with a metal sulfonate group of 3 to 6 mol % and polyester(B), and further exemplifies a stretch non-woven fabric produced byblending a polyester fiber having a low melting point in the conjugatefiber. However, each of them does not teach a two-way stretch fabricproduced by using side by side conjugate fibers.

As described above, a fabric, which has enough two-way stretchingability, a low stress for the stretching rate and further has astretching property of soft follow-up property, has not been available.

Accordingly, an object of the present invention is to provide a fabricwhich has a low stress for the stretching rate and has a soft andfollowing-up stretching property and also has an excellent dyeingproperty in a commercial scale production.

DISCLOSURE OF THE INVENTION

The present invention has accomplished the above-mentioned object byutilizing the three dimensional crimping property of a special conjugatefiber and the fabric of the present invention is characterized bycomprising a polyester conjugate fiber in an amount of at least 30weight %, which is prepared by conjugate spinning a polyethyleneterephthalate (component A) copolymerized with a structural unit havinga metal sulfonate group in a ratio of 1.5 to 6.0 mol % and apolyethylene terephthalate or polybutylene terephthalate (component B)in side by side method and drawing the product.

The conjugate fiber is comprised in the fabric in the state of having abirefringence of 90×10⁻³ to 195×10⁻³ and being three dimensionallycrimped so that said fabric has a stretching rate in both thelongitudinal direction and the lateral direction within the followingpercentage range: ##EQU1## wherein L₁ is the vertical length of thespecimen of a definite length and 5 cm wide when loaded by 5 g weightand L₂ is the vertical length of said specimen when loaded by a givenweight, which is 240 g when said fabric is non-woven fabric and 1500 gwhen said fabric is woven or knitted fabric.

The component A of the polyester conjugate fiber used in the presentinvention can be prepared by a procedure in which an ester formingcompound having a metal salt sulfonate group such as5-Na-sulfo-isophthalic acid, 5-K-sulfo-isophthalic acid,5-Li-sulfo-isophthalic acid, 4-Na-sulfo-phthalic acid,4-Na-sulfo-2,6-naphthalene dicarboxylic acid or an ester-formingderivative thereof is added to the polyethylene terephthalatemanufacturing process in a ratio of 1.5 to 6.0 mol %, preferably 2.0 to5.5 mol %, and then copolymerized. A small amount of other componentsalso may be copolymerized or blended if necessary.

Further, the component B is a polyethylene terephthalate or polybutyleneterephthalate. A small amount of other components may also becopolymerized or blended if necessary.

The polyester conjugate fiber can be prepared by combining side by sidethe component A and the component B and conjugate spinning and drawingit. However, in the case it contains less than 1.5 mol % of the unit ofthe component A having metal salt sulfonate group, the three dimensionalcrimping by the heat treatment is reduced and the stretching property ofthe product becomes insufficient. On the other hand, when it containsmore than 6.0 % of the unit, both the fiber strength and the meltingpoint are lowered to cause practical disadvantages.

The fabric of the present invention can be prepared by the procedure inwhich a raw fabric containing such conjugate fiber in a ratio of notless than 30 weight % is prepared and then heat-treated to give enoughthree dimensional crimping to the above mentioned conjugate fiber of thewhole fabric in both the longitudinal and lateral directions. However,it is important to effect the heat treatment of the raw fabric by anirradiation of far-infrared rays under a relaxed condition of the rawfabric.

It is necessary to use conjugate fibers prepared by conjugate spinningand subsequent drawing which have a molecular orientation structurehaving a birefringence in the range of 85×10⁻³ to 190×10⁻³, preferably90×10⁻³ to 175×10⁻³, measured by using tricresyl phosphate as thedipping solution. Conjugate fibers having a birefringence of less than85×10⁻³ or more than 190×10⁻³ can not provide a fabric superior instretching property by the heat treatment.

As the birefringence of the conjugate fiber may be somewhat enhanced bythe heat treatment, the conjugate fiber having the birefringence in theabove mentioned range provides a fiber having a birefringence in therange of 90×10⁻³ to 195×10⁻³ in the fabric product.

The polyester conjugate fiber, which has a latent three dimensionalcrimp peculiar to a conjugate fiber to suppress the bulkiness,mechanically crimped in appearance and heat-treated to shift thetemperature at which the three dimentional crimp starts to a higherlevel, is preferably used as the raw material for the preparation ofcross web, random web and spinning yarn.

Namely, as the conjugate fiber prepared by conjugate spinning andsubsequent drawing, there is preferably used that which is heat treatedunder tension at 140° to 170° C. to give a practical linear shrinkage of0.5 to 5% and mechanically crimped to give a crimpness of 8˜13/inch,preferably 9˜11/inch.

The raw fabric of the present invention may contains not less than 30weight % of the polyester conjugate fiber. Known fibers such as naturalfibers, semisynthetic fibers and synthetic fibers may be mixed at aratio of 70˜0 weight % to the 30˜100 weight % of said conjugate fiber.It is impossible to give a fabric having a longitudinal stretching rateof not lower than 9% at a mixing ratio of the polyester conjugate fiberof lower than 30 weight %.

Among the fibers which may be used together with the polyester conjugatefiber for preparing the fabrics, there are included cotton, wool, down,linen ramie, silk, viscose rayon fiber, acetate fiber, polyamidesynthetic fiber, polyester synthetic fiber, polyacrylonitrile syntheticfiber, polyethylene fiber, polypropylene fiber, polyvinyl alcoholsynthetic fiber, polyvinyl chloride fiber, polyvinylidene chloridefiber, polyurethane fiber, a binder fiber containing hot meltcomponents, glass fiber, carbon fiber, natural pulp, synthetic pulp andthe like. A slit film may be used.

The process for preparing raw fabrics is different for non-woven fabricsand woven or knitted fabric.

The raw non-woven fabric is prepared by mixing these raw materials in adefined ratio and blending and opening the mixture to form a web. Theeffective methods for web formation include carding process, Garnetprocess, air lay process and the like. Furthermore, the resultant crossweb and random web may be pre-bonded by a needle punch process or spunrace process, processed by stitch bond process or applied with anacrylic resin and the like by spraying or immersing process.

Further, the non-woven fabric may be prepared by a wet process with useof short cut fibers of 5 to 10 mm.

Contrary to it, woven and knitted fabrics are prepared by using the spunyarn made by a procedure in which the above mentioned materials aremixed in a defined ratio, opened, carded, drafted and then subjected toa known spinning process such as ring spinning, open-end spinning,air-jet spinning and the like. The spun yarn is a latent conjugatecrimped yarn with no stretching and accordingly can be very easily wovenor knitted. It is important for the design of gray woven fabric with useof the spun yarn that the void percentage of the yarn arrangementdefined by the following equation is made to be at least 45%, preferablynot lower than 50% in both the warp and weft directions. The voidpercentage of lower than 45% does not produce good stretch fabric.Especially, it is important for the preparation of the stretch fabrichaving no seam-slipping property to set the above-mentioned voidpercentage in the range of 53 to 72%. ##EQU2## where N: English countconverted to single fiber

S: Density of the spun yarn (g/cm²)

P: Punching density/inch. (The number is counted under the condition ofa loading weight of 1500 g to 5 cm of the fabric in each of the warp andweft directions.)

The fabric of the present invention can be made into a product having astretching rate of at least 9% by a procedure in which the polyesterconjugate fiber as mentioned above is shrunk by the development of firmthree dimensional crimping (number of crimps: 30˜50/inch) by heattreatment and converted to a coiled shape with which other componentsare involved.

A fabric having a stretching property only in the longitudinal directioncan be continuously manufactured by heat-treating a raw fabric asmentioned above with a known hot air drier, short loop steamer or hotair shrink drier at an appropriate temperature. However, it is possibleto continuously manufacture a fabric having a uniform stretching rate ofat least 9% in both of the longitudinal and lateral directions by theapplication of the conventional heat treating equipment and conditionsas described above.

Thus, the present invention makes it possible to manufacture fabricshaving a uniform high stretching rate in both directions by a procedurein which the raw fabric is shrunk in both the longitudinal and lateraldirections in a heat treating zone in consequence of which the rawfabric is fed to the heat treating zone in a relaxed state so that theraw fabric can move in both directions following the shrinking force, atthe same time applying far infrared radiation in the heat treating zone.

First, the heat source will be discussed in detail. As the polyesterconjugate fiber used in the present invention has a heat shrinkingproperty and a heat set property, it is preferred to give the heatshrinkage in as low a temperature range as possible, because the heatset property is enhanced in a high temperature region to involve theeffect even of a weak tension and to give an insufficient shrinkage.This is especially important for the longitudinal shrinkage of thefabrics.

A heat treatment in which hot air or steam as the heat source isdirectly blown to the raw fabric provides a shrinkage startingtemperature of 100° C. and a shrinkage completing temperature of 200° C.This phenomenon is caused by the fact that heat is given to the interiorof the polyester conjugate yarn of low thermal conductivity by heattransfer and convection. The period required is thus as long as 30 sec.at 180° C. Further, the definite cause of failure is that the hot airpressure or the steam pressure gives tension to the raw fabric and theheat set progresses under the tension so that a sufficient shrinkage cannot be attained.

Contrary to it, in the case far-infrared ray is used as the heat source,the shrinkage starting temperature is lowered to 64° C. which is thesecondary transition point of the polyester conjugate fiber, and theshrinkage completing temperature becomes 160° C. The period required isonly 10 sec. at 160° C. This is because the heat is given by directradiation and far-infrared ray is absorbed to the interior of thepolyester conjugate fiber with no medium. The wave length offar-infrared ray lies usually between 4 and 400 μm and the absorptionwave length of the polyester conjugate fiber is present in the range of5.7 to 15 μm. The fiber absorbs the far-infrared ray of this wave lengthand the molecular movement is generated to evolve the internal heatingat the temperature not lower than the secondary transition point.

Accordingly, in the method of the present invention, it can be avoidedto use the heat set temperature range of 170° to 200° C. commonly usedfor the polyester fiber and further shrinkage in both the longitudinaland lateral directions can be completed in a short period under acondition in which no tension is afforded to the fabric. The temperatureat the radiation zone is necessary to ease the molecular movement forcompleting the shrinkage of the polyester conjugate fiber. In the caseof non-woven fabric, it may be varied according to the raw materialratio in the raw fabric, the extent of needling, the resin inpregnationrate, the weight of the non-woven fabric and the like. In the case ofwoven fabric, it may be varied according to the blending ratio of spunyarn, the count of warp and weft and the like. In the case of knittedfabric, it may be varied according to the blending ratio of spun yarn,the size of stitch and the like.

In order to complete the full shrinkage, it is preferred to set theatmospheric temperature around the fabric at 80° to 110° C. for crossweb and random web by carding process, at 90° to 130° C. for prepunchedcross web, random web and raw knitted fabric, at 120° to 160° C. forfull-punched cross web and random web, and at 120° to 160° C. for theraw non-woven fabric impregnated by 6% acrylic resin and raw wovenfabric. The temperature can be controlled by adjusting the heat sourceon the back-side of the ceramic of the far-infrared ray generator. Whenthe far-infrared ray is generated by electric power, it can be achievedby on-off control or by voltage control with a thyristor.

The time required for the completion of heat shrinkage may be only 10 to15 sec. The fabric moves forward accompanied by a shrinking motion inboth the longitudinal and lateral directions during irradiation by thefar-infrared ray. It is preferred to adjust the initial radiation zonetemperature to a level lower than the next irradiation zone temperatureby about 10° C. so that it gets shrinkage in 2 or more steps, such asthe first step and the second step, rather than to generate a largeshrinkage at one step.

In the case of raw non-woven fabrics containing moisture previously, thedrying and heat treatment for shrinkage can be realized at the sametime.

Woven fabrics or knitted fabrics are treated by conventional processsuch as desizing, scouring, bleaching, dyeing and the like. Though thefabrics are thus heat-treated, they do not result in a good two-waystretch textile, because of receiving a longitudinal high tension in theabove conventional process.

In the method of the invention, such a treated fabric is fed to the heattreating equipment of the invention as the raw woven fabric or the rawknitted fabric, in which the shrinkage by crimping is recovered. It ispreferred to supply the raw fabric in wet condition so that the dryingand the shrinkage are completed simultaneously.

Now, the relaxed condition will be described.

According to the present invention, the heat treatment is carried out byfar-infrared ray irradiation. However, it is impossible to manufacturecontinuously on a commercial scale two-way stretch fabric only by thetreatment.

It is important to maintain the whole raw fabric in a relaxed state sothat the fabric can move in both the longitudinal and lateral directionsfollowing the shrinkage rate given in the heat treating zone for theirradiation by far-infrared ray. Especially, the followability in thelongitudinal direction is important.

For the purpose, the fabric should be over-fed corresponding to theshrinkage. It is important that the over-feed and the relaxed state arerealized in the longitudinal direction of the fabric in the heattreating zone.

Concretely, it is important that the contact area between the fabric andthe lattice is small so that the dynamic friction during the shrinkagemotion is low and that the fabric is fed to the heat treating zone undera relaxed state by forming a short loop in the fabric. A combination ofthese processes may be applied according to the weight of the objectivefabric. It is difficult to decrease the contact area between the fabricand the lattice in the case of using hot air or steam as the heatsource, which requires relatively long time for heat treatment. However,the far-infrared ray irradiation is very useful, because it decreasesthe heat treatment time, shortens the length of the heat treating andlowers the resistance against shrinkage due to the weight of the fabricand the zone length.

Further, it is also effective to use a bar type lattice or to use a gridtype lattice of wide opening for decreasing the contact area.

To lower the dynamic friction during the shrinkage motion, achromeplating or Teflon-coating may be applied on the bar or gridmaterial, or a rotary bar may be used. Further, in the case of non-wovenfabric, the shrinkage resistance due to the friction may be lowered byblending the polyester fiber surface-treated with silicone.Additionally, it is also effective to use a procedure in which a faintair stream is blown out of a multi-pore air nozzle bar fixed on thebootom of the lattice or a multi-pore air nozzle equipped on the lowerfar-infrared ray irradiation plate to float the fabric over the latticesurface and thus to lower the shrinkage resistance due to the selfweight of the fabric, or a procedure in which air is sucked by a nozzlehaving suction holes between the upper far-infrared ray irradiationplate to float the fabric over the lattice surface by about 1 mm duringthe heat treatment.

These methods are effective because the far-infrared ray is a radiationhaving the straight-going and reflective properties through no heatingmedium. In this case, the terminal of a temperature sensor can beinserted to the vicinity of the ceramic body of the far-infrared rayirradiation plate to control the temperature. It is the most preferablemethod to feed the raw fabric in the state of forming a short loop tothe heat treating zone.

Embodimently, a short loop may be formed while inserting the raw fabricmechanically between the lattice bars or while inserting the raw fabricbetween the lattice bars by air pressure blown out of the nozzle.

Alternately, a procedure may be effectively used in which the raw fabricis fed from the belt conveyor equipped to the upper surface of the gridlattice on the lattice and an air blow is applied on the fabric from thefixed multi-pore air nozzle in the lower part of the lattice to form ashort loop on the lattice.

It shall be noticed that the short loop should be formed by using theover-feed portion of the raw fabric. Mechanical or pneumatic tension maybe given to the short loop previously formed to form and keep the loop.However, it should be avoided to give a temperature of not lower than70° C. to the fabric in this step.

It is also important that the tension on the fabric generated by thepneumatic force is reduced by cancelling as combined as possible.

The shape of the short loop is controlled by the distance between theupper and bottom lattice conveyors and the air flow rate, and the shapeis set to match the over feed ratio depending on the shrinkability.

The fabric shrunk in the heat treating zone is cooled on the lattice onthe discharge side and dropped in a truck and then wound.

The resultant two-way stretch fabric of the present invention isheat-settable and thus can be subjected to a weight adjustment and astretching rate adjustement if required. For this purpose, it may betentered to a required width or tensioned by minus feed while blowinghot air or steam to afford a dimension set continuously.

In this case, a temperature higher than that previously applied in theheat treating zone of the present invention may be applied on thefabric. For example, hot air may be blown on it at 180° C. for 4 sec.under tension. Alternately, it can be set by being pressed with a hotroller or a press machine.

In the case the stretch raw fabric of the present invention contains atleast 60% of the polyester conjugate fiber and treated only in a drystate, it has a specific snacking property and shows a characteristicsuitable for use in the B-face body of the velvet type fastener. Thissnacking property can be removed by using steam in the dimension setprocess mentioned above.

For example, it is suitable to blow steam at 120° C. for 3 sec..Alternately, it may be heat treated under sprayed moisture, or it may beimmersed in hot water at a temperature not lower than 70° C. and thensqueezed by a roller and dried.

In the case a binder fiber containing hot melt components is blended inthe raw non-woven fabric of the present invention to thermally bond, thelow-melting components can be melted in the heat treating zone or thetentering heat set process of the present invention to complete thebonding.

The heat treatment of the present invention can be carried outcontinuously connecting to the preceeding process for the manufacture ofthe raw fabric and the succeeding heat set process and also handled as aseparate process in the lap supply process.

It is preferable for the heat treatment of the present invention to becarried out by a horizontal lattice. However, it may be carried out by alattice tilted forward, a lattice titled to the lateral direction or avertical type.

Now, the properties and the applications of the stretch fabrics preparedby the present invention will be illustrated.

The stretch fabric of the present invention is a set fabric in which theshrinkage is completed to a stable form at the heat treating temperatureor at a temperature not higher than the heat set temperature and has astretching property which extends following softly even to a weaktension to any direction and also a soft elongation recovery owing tothe strong three dimentional crimp. The stretching rate can be setbetween 9 and 160% at will according to the mixing ratio of the rawmaterials and the method for the preparation of raw fabric and thestretching recovery can be also set according to the mixing ratio of theraw materials and the method for the preparation of raw fabric.

Such a fabric of the present invention can be used for applicationsrequiring no stretching recovery and also for those requiring highstretching recovery.

For example, in the case the fabric is used as the deep moulding surfacematerial for the formation of a soft touch surface by adhering it on theuneven surface of plastics and on the surface of boxes, the stretchingproperty is necessary but the stretching recovery may be not necessary.

In such a case, the fabric of the present invention has such a heat setproperty that it can be set at the state by being adhered on thesubstrate as the surface material and heated to a temperature higherthan that of the heat treatment during its production and resultantlythe stretching recovery can be removed to give an uniform surface on thesubstrate surface.

Contrary to it, the object can be efficiently achieved by using a rawnon-woven fabric containing 5 to 35 weight %, preferably 6 to 25 weight% of a known low-melting fiber used for thermal bonding for applicationsin which a high stretching recovery and a rapid kick-back property witha low permanent set are required. In this case, a thermoplastic orthermoset three dimensional thermal bonding point is formed in thenonwoven fabric and, for example, the stretching recovery after 30 sec.can be set at 95 to 100%. And, the stretching rate also can be set inthe range of 9 to 160%.

Furthermore, when an elastic nonwoven fabric having a longitudinalstretching rate of 9 to 15% and a lateral stretching rate of 35 to 45%is required, the object can be accomplished by a procedure in which aweb is formed by mixing 40 to 50% of a known highly shrinkablenon-annealed synthetic fiber and then it is punched to obtain a rawnon-woven fabric.

Thus, as the fabric of the present invention has a two-way stretchingproperty designed for each purpose and a soft touch fitness, it canprovide products which gives no oppressive sensation nor resistance andwhich follows the movement of the body comfortably and gives good geeland which has excellent draping and fitting properties when used forclothings.

This advantage is based on the facts that the polyester conjugate yarnused for the present invention contains a cation-dyeable polyester ascomponent A and thus it has a lower Young's modulus than a usualpolyester, and that the birefringence of the polyester conjugate fiberis in the range of 90×10⁻³ to 195×10⁻³ as a result of the limitation ofits increase by 5×10⁻³ to 25×10⁻³ and by heat-treating with far-infraredray absorption and that a sufficient morphologic change realizing heatshrinkage and a high three dimensional crimp rate is attained.

Furthermore, the stretch fabric of the present invention can be usedhighly effectively for the following applications utilizing itscharacteristics.

(1) It has little nap on the surface and has an excellent anti-pillproperty. Accordingly, it can be efficiently punched out and cut. It canbe used as a comfortable clothing material superior in elongationrecovery, as a stretch padding cloth following the movement of the facematerial and giving no physical disorder, or a stretch base material forcomposite compresses which is used by coating various ointments ormedicines. This effect is based on the facts that the heat treatment ofthe present invention gives the polyester conjugate fiber a fullshrinkage so that the fiber winds spirally the other fiberssimultaneously with the development of coiling to give a flat naplesssurface, that the internal fiber structure shows an orientation in whichthe birefringence of the polyester conjugate fiber after heat-treatmentis limited within the range of 90×10⁻³ to 195×10⁻³ and that the singlefiber strength is in the range of 1.8 to 3.8 g/d.

(2) The fabric of the present invention has an excellent stretchingability in both of the longitudinal and lateral directions and shows ahigh bulkiness with the high crimping property. The volume recovery ofthe fabric of the present invention after being heavily loaded isespecially good and thus it maintains a high air content and shows asoft and high thickness. Accordingly, it can be used for soft clothingmaterials superior in stretching property and easily movable, such asunderwear, winter sport wears, working clothes, winter clothes,operating gown and the like, and for stretching materials such ascushioning materials, padding materials for furniture, padding materialsfor seat, wipers, carpets, shock-absorbing padding materials for sports,joint tapes for medical care and the like.

(3) As the fabric of the present invention is superior in both ofstretching and shrinking properties and has high density. Accordingly,it has an excellent filter property, and it is useful for masks, moldedmasks, filter clothes, air filters, filters for liquid and the like.

(4) As the fabric of the present invention has a high water-holdingcapacity and a high anti-wet back property in addition to the stretchingproperty, it is suitable for liquid storage. It is useful for absorptionpaddings for oil separation, battery separators, menstrual napkins,dipers and the like.

(5) As the fabric of the present invention has a heat-setting propertyin addition to the stretching property in both directions, it can bepartly deformed with a mould, heat-treated and shaped threedimensionally into several forms. It can be widely used for shoulder padmaterials, core or interlining materials, basking materials, foundationmaterials and the like.

(6) As the fabric of the present invention is superior in heatresistance, light resistance and chemical resistance and also can bedyed to a deepcolor with cationic dyes and dispersion dyes even underatmosphereic pressure, it can be widely used for clothing and severaldecorative mats.

(7) As the fabric of the present invention is superior in stretchingrecovery and crease recovery, it can be used durably for mats orcoverlets for a foot warmer, packaging materials and the like.

(8) The fabric of the present invention can be variously finished toproduce useful products. They include a large cushion molding which isprepared by laminating the fabric comprising heat melting fibers,cutting the product, integrating several cut sheets and thermalrebonding in a mold, a synthetic leather superior in stretching propertywhich is produce by impregnating or coating a styrene-butadienesynthetic latex or urethane synthetic latex, an elastic water-absorbingsynthetic leather having a PVA-acetal film, and the like. Further, thenon-woven fabric of the present invention can be further finished bysuch as needle-punching, impregnation with an acrylic resin, physicaltreatment with an embossing roller, compression molding with a pressplate, laminating or needling with at least one of known non-wovenfabrics, woven fabrics, knitted fabrics, films and papers on one side oron both sides or at both end.

(9) As the woven and knitted fabrics of the present invention are softand superior in stretching property in all directions, and can be dyedwith cationic dyes, they are useful for a material for sports wears suchas tennis wears, baseball wears, ski wears and the like, working wears,trunks, shorts, shirts, interliner and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

Each of FIGS. 1 to 4 is the flow diagram showing respectively oneembodiment of the heat treating process according to the presentinvention.

FIG. 5 shows a load-stretching rate curve of the non-woven fabric in anexample of the present invention.

BEST MODE OF EMBODYING THE INVENTION

Now, the present invention will be illustrated in details by Examples.The methods for the measurement of the physical properties in Exampleswere in accordance with the followings.

(1) Intrinsic Viscosity [η]

The relative viscosity (η_(rel)) at 20° C. is measured using a mixedsolvent containing equal weight of phenol and tetrachloroethane and theintrinsic viscosity is calculated by the following equation. ##EQU3##wherein coefficient K=0.37 and concentration C=1 g/100 cc.

(2) Stretching Rate and Stretching Recovery

The test is carried out with use of Tensilon in the condition of asample clamping length of 10 cm, a sample width of 5 cm and a head speedof 5 cm/sec. The sample is elongated under an initial load of 5 g andstood for 1 min. to measure the vertical length L₁.

Then the sample which is a non-woven fabric is loaded with 240 g andstood for 1 min. to measure the vertical length L₂ and the load isreleased and the stress is relaxed for 3 min. Further the loading of 5 gis repeated and stood for 1 min. to measure the vertical length L₃. Thesample which is a woven or knitted fabric is loated with 1500 g andstood for 1 min. to measure the vertical length L₂ and the load isreleased and the stress is relaxed for 60 min. Further the loading of 5g is repeated and stood for 1 min. to measure the vertical length L₃.

Stretching rate and stretching recovery are calculated by the followingequations. ##EQU4##

(3) Linear Shrinkage Percentage

This is measured according to JIS L 1015 7.15. (2) at 170° C. for 15min. with initial load=denier×50.

(4) Number of Crimp

This is measured according to JIS L 1015 7.12.1.

(5) Percentage of Crimp

This is measured according to JIS L 1015 7.12.2.

(6) Denier

This is measured according to JIS L 1015 7.5.1A.

(7) Strength and Elongation

This is measured according to JIS L 1015 7.7.1.

(8) Birefringence

This is measured by a polarization microscope equipped with a beleckcompensator with use of tricresyl phosphate as the dipping solution.

(9) Density of Spun Yarn

There is used the following values measured by a density gradient tube.

    ______________________________________                                        Cotton              1.5                                                       Rayon               1.5                                                       Wool                1.32                                                      Silk                1.39                                                      Polyester           1.38                                                      Hemp                1.50                                                      Polyester conjugate fiber                                                                         1.38                                                      according to the present                                                      invention                                                                     ______________________________________                                    

As the blending ratio, a weighted mean with the mixing ratio is used.

PREPARATION OF POLYESTER CONJUGATE FIBERS Preparation 1

A polyethylene terephthalate copolymer in which 2.5 mol % of 5-sodiumsulfo-isophthalic acid was compolymerized and had an intrinsic viscosityof 0.529 was used as component A, and a polyethylene terephthalatehaving an intrinsic viscosity of 0.634 was used as component B. Anun-drawn yarn was prepared by conjugate-spinning these components inside by side of a volume ratio of 1:1 at 290° C. and drawn to 2.4 ratio.The drawn yarn was annealed under tension at 160° C. and thenmechanically crimped. The resultant polyester conjugate fiber (C-1) of2.2 denier and 51 mm cut length had a strength of 3.3 g/d, an elongationof 55%, a crimp number of 11/inch, a crimpness of 19% and abirefringence of 95×10⁻³.

Preparation 2

A polyethylene terephthalate copolymer in which 5.1 mol % of 5-sodiumsulfo-isophthalic acid was compolymerized and had an intrinsic viscosityof 0.47 was used as component A, and a polyethylene terephthalate havingan intrinsic viscosity of 0.685 was used as component B. An un-drawnyarn was prepared by conjugate-spinning these components in side by sideof a volume ratio of 1:1 at 285° C. and drawn to 2.5 ratio. The drawnyarn was annealed under tension at 150° C. and then mechanicallycrimped. The resultant polyester conjugate fiber (C-2) of 4.0 denier and51 mm cut length had a strength of 2.0 g/d, an elongation of 71.5%, acrimp number of 9.2/inch, a crimpness of 18% and a birefringence of105×10⁻³.

Preparation 3

A polyethylene terephthalate copolymer in which 2.3 mol % of 5-sodiumsulfo-isophthalic acid and 3.2 mol % of butanediol were compolymerizedand had an intrinsic viscosity of 0.463 was used as component A, and apolybutylene terephthalate having an intrinsic viscosity of 0.660 wasused as component B. An un-drawn yarn was prepared by conjugate-spinningthese components in side by side of a volume ratio of 0.9:1.0 at 280° C.and drawn to 2.6 ratio. The drawn yarn was annealed under tension at145° C. and then mechanically crimped. The resultant polyester conjugatefiber (C-3) of 3.0 denier and 64 mm cut length had a strength of 2.5g/d, an elongation of 52%, a crimp number of 10/inch, a crimpness of 20%and a birefringence of 134×10⁻³.

Preparation 4

A polyethylene terephthalate copolymer in which 2.9 mol % of 5-sodiumsulfo-isophthalic acid was compolymerized and had an intrinsic viscosityof 0.450 was used as component A, and a polyethylene terephthalatecopolymer in which 4 mol % of isophthalic acid was compolymerized andhad an intrinsic viscosity of 0.660 was used as component B. An un-drawnyarn was prepared by conjugate-spinning these components in hollow sideby side at 290° C. and drawn to 2.6 ratio. The drawn yarn was annealedunder tension at 160° C. and then mechanically crimped. The resultantpolyester conjugate fiber (C-4) of 6.5 denier and 64 mm cut length had astrength of 3.0 g/d, an elongation of 56%, a crimp number of 9/inch, acrimpness of 21%, a hollowness of 24% and a birefringence of 158×10⁻³.

HEAT-TREATMENT FOR FABRICS Treatment 1

This treatment is carried out with use of the equipment shown in FIG. 1,in which a rolled raw non-woven fabric (D) set on a delivery roller (1)in supply zone (I) of the fabric is overfed to the shooter (3) throughfeed rollers (2) and overfed continuously on a bar conveyor (5) havingbars arranged at equal spaces at the outlet of a shooter (3).

The bar conveyor (5) runs endlessly by rotation of conveyor chain wheels(4) and air blow pipes (6) equipped weftwise parallel below the upperportion of the bar conveyor (5) blows an appropriate amount of air. Theraw non-woven fabric (D) forms an uniform peak in lateral direction bythe air blow so that the feeding amount in the direction of progress(longitudinal direction) is controlled constant.

The raw non-woven fabric (D) passed on the air blow pipe (6) forms ashort loop of a definite length between the bars and is sent to thesubsequent heat treating zone (II). Far-infrared ray irradiation plates(7) are arranged above and below the bar conveyor (5) in the heattreating zone (II) and the distance between each far-infrared rayirradiation plate (7) and the bar conveyor can be varied appropriatelyand also the temperature can be controlled by a voltage controller.

The non-woven fabric (D) entered into the heat treating zone (II)absorbs radiation of wave length 3 to 50 μm in the spectrum range offar-infrared ray to give a molecular vibration so that the non-wovenfabric (D) is heated internally and shrunk rapidly in both oflongitudinal and lateral directions at the same time. As a result, thenon-woven fabric (D) having a short loop on the bar conveyor (5) in thelongitudinal direction becomes flat as the shrinkage proceeds and thelateral shrinkage also goes on to complete the shrinking process.

Then the non-woven fabric passed through the heat treating zone (II) iscooled with air blown from the air blow pipe (6) equipped below the barconveyor (5) at outlet of the heat treating zone (II), dropped on ashooter box (8) and then put between nip rollers (9) of the take-up zone(III) and wound on a take-up roller (10).

Treatment 2

This treatment is carried out with use of the equipment shown in FIG. 2,in which a non-woven fabric (D) fed to an overfeed conveyor (5a) insupply zone (I) of the non-woven fabric is floated by air blown from airblow plates (6a) and (6b) approx. 1 cm over the conveyor. The barconveyor (5a) of supply zone (I) moves faster than the bar conveyor (5b)of heat treating zone (II) and thus an overfeed corresponding to thewarpwise shrinkage of the non-woven fabric (D) in heat treating zone(II) is accomplished.

Next, far-infrared ray irradiation plates (7) are arranged above andbelow the bar conveyor (5b) in heat treating zone (II), in which thedistance between each far-infrared ray irradiation plate (7) and the barconveyor (5b) can be varied appropriately and also the temperature canbe controlled by a voltage controller.

Further, suction holes (11), a suction duct (12) and a suction fan (13)are equipped in the upper portion of heat treating zone (II) to floatthe non-woven fabric over the bar conveyor (5b) by approx. 2 mm bysuctioning and thus to ease the shrinkage movement of the non-wovenfabric.

Thus, the raw non-woven fabric (D) entering heat treating zone (II)absorbs radiation of wave length 3 to 50 μm in the spectrum range offar-infrared ray to give a molecular vibration so that the non-wovenfabric is internally heated and shrinks rapidly in both the longitudinaland lateral directions at the same time. As a result, the raw non-wovenfabric (D) moves uniformly in both directions as the shrinkage proceedsto complete the shrinking process. The non-woven fabric passed throughheat treating zone (II) is cooled by air blown from a cooling air blowplate (6c) and then transferred to a plate conveyor (14) and cut by acutter (15) to a required shape.

Treatment 3

This treatment is carried out with use of the equipment shown in FIG. 3,in which a rolled raw non-woven fabric (D) set on a delivery roller (1)in supply zone (I) of the non-woven fabric is overfed through a feedroller (2) to a rough loop-holding grid (16) coated by Teflon. The rawnon-woven fabric (D) is passed through inlet guide rods (17) of heattreating zone (II), through far-infrared ray irradiation plates (7) andthen through outlet guide rods (18) and pressed to an appropriatethickness by hot rollers (19) to give a smooth surface. Further, thenon-woven fabric (D) is passed through between guide rods (21) of a heatinsulating plate (20), sucked on a suction cooling drum (22) to beair-cooled, then held by nip rollers (23) of take-up zone (III) andwound by a take-up roller (10). In heat treating zone (II), the rawnon-woven fabric (D) is sent upward between the far-infrared rayirradiation plates (7) equipped vertically by floating power of anascending air current and uniformly absorbs radiation of a wave lengthof 3 to 50 μm in the spectrum range in the far-infrared ray irradiationplates (7) from both sides under a relaxed state to give molecularvibration so that the non-woven fabric (D) is internally heated andrapidly shrinks in both directions at the same time.

The surface temperature of the lower far-infrared ray irradiation plates(7a) is set lower than that of the upper far-infrared ray irradiationplates (7b) to prevent a sudden high shrinkage. The distance between thepaired far-infrared ray irradiation plates (7a) or (7b) can be varied.In the vertical heat treating zone of this type, nothing inhibits theirradiation of the far-infrared ray and a uniform shrinkage in bothdirections can be completed continuouly.

An overfeeding corresponding to the shrinkage is provided continuouslyby giving a difference between peripheral velocities of the suction drum(22) and the feed roller (2) and the raw non-woven fabric (D) is held ina looped state in the loop-holding grid (16) and is ready for thesubsequent step. The hot roller (19) is rotated in the same peripheralvelocity as the suction drum (22), but in some cases it is uncoupled fordisuse. As air is heated with the far-infrared ray irradiation plates(7a) and (7b) to generate an ascending air current, the heat insulatingplate (20) is provided to prevent its entry into the subsequent portioncomprising the suction cooling drum (22) and thus to give no difficultyon cooling the non-woven fabric.

Treatment 4

This treatment is carried out with use of the equipment shown in FIG. 4,in which a rolled raw fabric (D) set on a delivery roller (1) in supplyzone (I) of the fabric is overfed on a net conveyor (24) through a feedroller (2).

The net conveyor (24) runs endlessly and an upper net (25) is arrangedabove it. Far-infrared ray irradiation plates (7) are arranged in theback of each net and it is controlled by adjusting the surfacetemperature by voltage controlling with use of a temperature sensor inthe heat treating chamber.

Air blow pipes (6) are arranged between each element of the far-infraredray irradiation plates (7) parallel to the width direction (weftdirection) and always take an appropriate amount of air of the heattreating chamber (27) and blows it. This air forms a short loop of theraw fabric between the two nets.

The raw fabric (D) entered to the heat treating zone (II) shrinksrapidly by the far-infrared ray irradiation. At this time, the warpwiseraw fabric (D) which has formed a loop on the net conveyor (24) becomesflat as the shrinkage proceeds and also it shrinks weftwise to completethe shrinkage process. The fabric passed through the heat treating zone(II) is then cooled with air blown from the air cooling nozzle (28)equipped on the upper portion of the net conveyor (24) at the outlet ofthe heat treating zone (II) and dropped to the shooter box (8) and thenput between the nip rollers (9) of the take-up portion (III) and woundon the take-up roller (10).

EXAMPLES OF STRETCH FABRICS EXAMPLE 1

The polyester conjugate fiber (C-2) of 4.0 denier and 51 mm lengthprepared in Preparation 2 and a usual polyester staple of 3 denier and51 mm cut length and a sheath & core type low-melting polyester of 2denier and 51 mm cut length (Kanebo's Ester/cotton Bel-Combi type 4080)were mixed together to the blending ratio shown in Table 1, opened andblended in an opening machine, then pneumatically conveyed, carded in acarding machine and drawn by a drafter to obtain a cross web of a crossangle of 30°, a width of 1500 g/m² and a weight of 50 g/m². One side ofthe cross web was slightly needled (28 needles/cm²) and wound in a rollform to obtain a raw non-woven fabric.

According to Treatment 1, this raw fabric was passed through the feedroller (2), overfed at the defined speeds as shown in Table 1, passedthrough the shooter (3), fed on the bar conveyor (5) at a rate of 5m/min., then passed on the air blow pipe to form a short loop and thensent to the heat treating zone (II) for far-infrared irradiation. Thetemperature in the heat treating zone (II) was set at 110° C. and thedistance between the far-infrared ray irradiation plates (7) was set at12 cm. The heat treating period was set at 17 sec.

The non-woven fabric passed through the heat treating zone (II) wascooled with the air blow pipe (6) equipped on the outlet side and thendropped to the shooter box (8) and put between the nip rollers (9) andwound continuously on the take-up roller (10). The physical propertiesof the resultant stretch non-woven fabrics are shown in Table 2. Theresults for comparative samples which were obtained in the same manneras in the samples 1 and 2 except that the heat treatment was carried outwith a hot air shrink drier are also shown in Table 2 as Controls 1 and2.

                  TABLE 1                                                         ______________________________________                                        Blending composition (weight %)                                                     Polyester          Low-                                                 Sample                                                                              conjugate Polyester                                                                              melting                                                                              Weight                                                                              Over-feeding                            No.   yarn      staple   polyester                                                                            g/m.sup.2                                                                           rate (%)                                ______________________________________                                        1     90         0       10     52    45                                      2     85         5       10     49    35                                      3     80        10       10     51    27                                      4     70        20       10     49    19                                      5     50        40       10     53    13                                      6     30        60       10     48     8                                      ______________________________________                                    

                                      TABLE 2                                     __________________________________________________________________________                Stretching                                                                          Stretching                                                                          Tensile                                                     Shrinkage                                                                           rate  recovery                                                                            strength                                                                            Birefringence                                   Sample                                                                              (%)   (%)   (%)   (%)   after heat                                      No.   Lon.                                                                             Lat.                                                                             Lon.                                                                             Lat.                                                                             Lon.                                                                             Lat.                                                                             Lon.                                                                             Lat.                                                                             treatment                                       __________________________________________________________________________    1     45 43 37 34 97 99 1320                                                                             1210                                                                             117 × 10.sup.-3                           2     35 32 30 28 95 97 1645                                                                             1463                                                                             114 × 10.sup.-3                           3     27 25 25 23 92 93 1521                                                                             1408                                                                             116 × 10.sup.-3                           4     19 17 15 13 85 86 1635                                                                             1325                                                                             118 × 10.sup.-3                           5     13 12 13 12 84 83 1782                                                                             1139                                                                             115 × 10.sup.-3                           6      8  8 11 10 78 77 2304                                                                             1912                                                                             118 × 10.sup.-3                           Control 1                                                                            1 45  6 36 72 89 1450                                                                             1361                                                                             119 × 10.sup.-3                           Control 2                                                                            0 34  4 31 74 85 1705                                                                             1508                                                                             120 × 10.sup.-3                           __________________________________________________________________________     Note:                                                                         Lon. means longitudinal direction.                                             Lat. means lateral direction.                                           

EXAMPLE 2

The polyester conjugate fiber (C-1) prepared in Preparation 1, which had2.2 denier and 51 mm length, was opened by an opening machine,pneumatically conveyed, carded by a carding machine and then drawn by adrafter to obtain a cross web of a cross angle of 40°, a width of 1500mm and a weight of 25.1 g/m². This web was immersed in an aqueousacrylic resin emulsion being a well known chemical binder, and thensqueezed with a roller to pick up 5% resin based on the fiber weight andthe moisture was removed continuously at 95° C. and the web was wound toget a raw non-woven fabric (D).

This non-woven fabric raw cloth (D) was continuously treated accordingto Treatment 3. The peripheral velocity ratio of the feed roller (2) tothe suction cooling drum (22) was adjusted to give an overfeeding rateof 34% and the peripheral velocity of the suction cooling drum (22) wasset at 3 m/min. Further, the distance between the opposing twofar-infrared ray irradiation plates (7a) and (7b) was set at 12 cm andthe temperature in the heat treating zone (II) was always controlled at125° C. by adjusting the voltage of the back side of irradiation plateswith the thyristor connected to the central sensor and the heattreatment period was 15 sec. The hot roller (19) at the outlet of theheat treating zone was set uncoupled for disuse.

The heat treated non-woven fabric was cooled by the suction cooling drum(22), passed through the nip roller (23) and wound continuously to thetake-up roller (10). Multipore air blow pipes were equipped to the inletguide rod (17) and the outlet guide rod (18) of the heat treating zone(II) and air was blown slowly from them to both sides of the non-wovenfabric at a right angle to effect the heat transfer prevention and therapid cooling after the heat treatment respectively.

The resultant non-woven fabric had a longitudinal shrinkage of 34% and alateral shrinkage of 35%. It showed a longitudinal stretching rate of46% and a lateral stretching rate of 47% and the birefringence of thefiber was 104×10⁻³.

The same non-woven fabric, which was heat-treated at 160° C. for 4 sec.with a well known short loop drier, showed a longitudinal shrinkage of2% and a longitudinal stretching rate of 5% and the birefringence of thepolyester conjugate yarn was 126×10⁻³.

EXAMPLE 3

50 weight % of the polyester conjugate fiber (C-4) prepared byPreparation 4, which had 6 denier and 64 mm cut length, 35 weight % ofwool and 15 weight % of a sheath & core type polyester fiber having 4denier and 64 mm cut length (melting point of the core: 225° C., meltingpoint of the sheath: 95° C.) were blended and opened with an openingmachine, then pneumatically conveyed, carded in a carding machine andpressed by a roller.

Thus, a laminated cross web of 2000 mm width and 420 g/m² weight wasprepared continuously in a rate of 6 m/min. and it was used as the rawnon-woven fabric. In this Example, the manufacturing equipment of thenon-woven fabric was connected directly to the equipment for Treatment 2to supply the continuously manufactured raw non-woven fabric (D) on theoverfeed conveyor (6a) subsequently. The overfeeding rate between thebar conveyor (6a) and the overfeed conveyor (6b) was set at 53%.

The distance between the far-infrared ray irradiation plates (7) was setat 14 cm and the temperature in the heat treating zone (II) wasmaintained at 110° C. by on-off control of the electric power sourcebehind the irradiation plates with the central sensor. The heattreatment period was 17 sec.

The heat-treated non-woven fabric was cooled by the air from the airblow plate (6c), transferred to the plate conveyor (14) inafter-treatment zone (III) and cut with the cutter (15) to be shaped toa defined shape, in which a rotary blade was applied warpwise and aguillotine blade was applied weftwise. The distance between bars in thebar conveyor (5b) was 80 mm and the diameter of the bar was 5 mm.

The resultant non-woven fabric showed a longitudinal shrinkage of 53%, alateral shrinkage of 33%, a longitudinal stretching rate of 12% and alateral stretching rate of 10%. The birefringence of the polyesterconjugate yarn in the non-woven fabric was 154×10⁻³.

EXAMPLE 4

80 weight % of the polyester conjugate fiber (C-3) of 3.0 denier and 64mm cut length prepared by Preparation 3, 20 weight % of 6 nylon of 2.0denier and 64 mm cut length were blended and opened by an openingmachine, then pneumatically conveyed and carded by a carding machine.The resultant web was blown on the mesh cylinder and sucked to obtain arandom web. The random web was needle-punched in the condition of 24needles/cm² and a needle depth of 8 mm to obtain a raw non-woven fabric(D) of 60 g/m².

This fabric was passed through the delivery roll (1) and continuouslytreated according to Treatment 3, in which the overfeed rate of thefabric was set at 26% by controlling the peripheral velocity ratio ofthe feed roller (2) against the suction cooling drum (22) and theperipheral velocity of the suction cooling drum (22) was operated at 3m/min.

The distance between the opposing far-infrared ray irradiation plates(7a) and (7b) was set at 12 cm and the temperature in the heat treatingzone (II) was controlled at 130° C. by controlling the voltage behindthe irradiation plate by the thyristor connected to the central sensor.The heat treatment period was 15 sec.

The surface temperature of the hot rollers (19) at the outlet of theheat treating zone was set at 130° C. and the fabric was pressed by themto make the surface smooth. The peripheral velocity of the hot rollers(19) was set at the same level as that of the suction cooling drum (22).

The heat treated non-woven fabric was cooled in the suction cooling drum(22), passed through the nip roller (23) and wound continuously by thetake-up roll (10).

The resultant non-woven fabric showed a longitudinal shrinkage of 26%, alateral shrinkage of 53.6%, a longitudinal stretching rate of 31% and alateral stretching rate of 42%. The birefringence of the polyesterconjugate yarn in the non-woven fabric was 136×10⁻³.

The longitudinal load-stretching rate curve of this non-woven fabric isshown in FIG. 4 as (a). The longitudinal load-stretching rate curve ofthe non-woven fabric prepared by a same method using 18% of thepolyester conjugate fiber and 82% of 6-nylon is shown in FIG. 4 as (b).

EXAMPLE 5

A noncrimp short cut fiber of 10 mm cut length, which was prepared bycutting the drawn tow prepared in Preparation 1, had a birefringence of96×10⁻³. 70 parts of this fiber, 30 parts of a polyester fiber of 0.8denier and 5 mm cut length, 15 parts of a sheath & core low-meltingpolyester of 2 denier and 5 mm cut length (Kanebo's Ester/CottonBel-Combi type 4080) and 10 parts of a dispersant for paper-making wereadded to 100,000 parts of water and dispersed in it. Then the dispersionwas flowed on a moving mesh net in a constant rate to remove water bysuction to obtain a raw non-woven fabric (D).

The manufacturing equipment of the raw non-woven fabric (D) was directlyconnected to the equipment of Treatment 1 and the raw non-woven fabric(D) was continuously fed on the bar conveyor (5) of a bar diameter of 5mm and a bar distance of 70 mm at a rate of 5 m/min. and an overfeedrate of 36% and supplied to the heat treating zone (II) while forming ashort loop.

The heat treatment in the heat treating zone (II) was carried out in acondition that the temperature of the zone was 130° C., the distancebetween the far-infrared irradiation plates (7) was 12 cm and the heattreating period was 17 sec.

The non-woven fabric passed through the heat treating zone (II) wascooled by the air blow pipe (6) equipped on the outlet side, thendropped to the shooter box (8), put between the nip rollers (9) andwound continuously to the take-up roller (10).

The resultant non-woven fabric had a weight of 60 g/m², a longitudinalstretching rate of 36% and a lateral stretching rate of 32% and thebirefringence of the polyester conjugate yarn was 115×10⁻³.

EXAMPLE 6

84 parts of a polyester conjugate fiber (C-1) of 2.2 denier and 51 mmlength, which was prepared in Preparation 1, and 16 parts of a sheath &core fiber of the blend ratio of 1:1 of 2.0 denier and 51 mm length, inwhich the core was a polyethylene terephthalate and the sheath was apolyethylene terephthalate copolymer containing 16% isophthalic acidcomponent, were mixed and blended, carded, drawn, roved, and fine-spunto obtain a spun yarn of English count of 30'S/1. It was used as theweft yarn. On the other hand, this spun yarn was beamed and sized toobtain the warp yarn. A gray fabric of a warp density of 35 yarns/inch,a weft density of 35 yarns/inch and 44 inch wide was prepared from them.

The fabric was scoured at 90° C. for 30 min., dried and heat treatedaccording to Treatment 4. The overfeed rate was set at 45% and the speedof the net conveyor was set at 10 m/min and the fabric was passed abovethe air blow pipe to form a short loop and sent to the far-infraredirradiation zone (II).

The temperature in the heat treating zone was 150° C. and the heattreatment period comprising drying process was 60 sec. The fabric passedthrough the heat treating zone (II) was cooled by the air cooling nozzleequipped on the outlet side and then dropped in the shooter box (8) andput between the nip rollers (9) and wound continuously by the take-uproller (10).

The resultant woven fabric had a warp shrinkage of 35%, a weft shrinkageof 38%, a warp stretching rate of 29% and a weft stretching rate of 30%.The birefringence of the polyester conjugate yarn of the fabric was155×10⁻³.

EXAMPLE 7

84 parts of a polyester conjugate fiber (C-1) of 2.2 denier and 51 mmlength prepared in Preparation 1 and 16 parts of a polybutyleneterephthalate fiber of 3.0 denier and 51 mm length were mixed andblended, carded, drawn, roved, and fine-spun to obtain a spun yarn ofEnglish count of 30'S/1. It was made into a two ply yarn, which was usedas the warp and the weft to prepare a twill fabric at a warp density of64 yarns/inch and a weft density of 58 yarns/inch. The void percentageof the warp was 61.7% and the void percentage of the weft was 64.7%.

The fabric was scoured at 95° C. for 20 min., dried and then dyed instream at 120° C. for 60 min. After drying, the dyed fabric was treatedaccording to Treatment 4, in which the overfeed rate was set at 26%, thenet conveyor speed was set at 10 m/min and the fabric was passed abovethe air blow pipe to form a short loop and sent to the far-infraredirradiation zone.

The fabric passed through the heat treating zone (II) at 150° C. for 45sec. was cooled by the air cooling nozzle equipped on the outlet sideand then dropped in the shooter box (8) and put between the nip rollers(9) and wound continuously by the take-up roller (10).

The resultant woven fabric had a warp shrinkage of 23%, a weft shrinkageof 25%, a warp stretching rate of 17% and a weft stretching rate of 19%and a weight of 268 g/m². The birefringence of the polyester conjugateyarn of the fabric was 157×10⁻³. The stitch slipping resistance under 12kg load according to JIS L 1096 B method was 1.8 mm in both directions.

EXAMPLE 8

The polyester conjugate fiber (C-1) of 2.2 denier and 51 mm length wasopened and picked, carded, drawn, roved, spun to give a spun yarn ofEnglish count of 20'S/1. It was mixed with 100% cotton spun yarn of20'S/1 in a ratio of 1:1 and a dappled face knitted fabric was preparedusing a 18 gauge round knitting machine. The weight of the knittedfabric was 130 g/m².

The fabric was scoured, bleached with hydrogen peroxide, dyed in streamat 120° C. for 60 min. with a fluorescent dye, centrifugally dehydrated,cut and opened and then heat-treated according to Treatment 4.

The overfeed rate was set at 20% and the speed of the net conveyor wasset at 5 m/min and the fabric was passed above the air blow pipe to forma short loop and sent to the far-infared irradiation zone.

The fabric passed through the heat treating zone (II) at 160° C. for 45sec. was cooled by the air cooling nozzle equipped on the outlet side,dropped in the shooter box (8), put between the nip rollers (9) andwound continuously by the take-up roller (10).

The resultant knitted fabric had a wale shrinkage of 18.2%, a courseshrinkage of 15.7%, a wale stretching rate of 3.5% and a coursestretching rate of 60.8% and a weight of 198 g/m². The birefringence ofthe polyester conjugate yarn of the fabric was 155×10⁻³.

INDUSTRIAL APPLICABILITY OF THE INVENTION

Each of the fabrics according to the present invention has a stretchingproperty of at least 9% in both of the longitudinal and lateraldirections and good feeling, and is superior in dying property and heatset property. Accordingly, they can be very effectively used for bothclothings and industrial materials.

What is claimed is:
 1. A method for the preparation of a fabric whichhas a stretching rate in both of the longitudinal direction and thelateral direction within the following range: ##EQU5## wherein L₁ is thevertical length of a specimen of a definite length and 5 cm wide whenloaded by 5 g weight and L₂ is the vertical length of said specimen whenloaded by a given weight, which is 240 g when said fabric is non-wovenfabric and 1500 g when said fabric is woven or knitted fabric,characterized in preparing by fiber intermingling, weaving or knitting araw fabric comprising a polyester conjugate fiber having a birefringenceof 85×10⁻³ to 190×10⁻³ in an amount of at least 30 weight % and a crimpnumber of 8 to 13/inch, which is produced by conjugate spinning apolyethylene terephthalate (component A) copolymerized with a structuralunit having a metal sulfonate group in a ratio of 1.5 to 6.0 mol % and apolyethylene terephthalate or polybutylene terephthalate (component B)in side by side method, drawing the product, and mechanically crimpingthe fiber to a crimp number of 8 to 13/inch, and irradiating the rawfabric with far-infrared rays in a relaxed condition to proceedthree-dimensional crimping of said conjugate fiber to produce a stretchfabric comprising said conjugate fiber having a birefringence of 90×10⁻³to 195×10⁻³.
 2. A method according to claim 1, wherein the number ofcrimp of said conjugate fiber is increased to 30 to 50/inch by saidfar-infrared irradiation.
 3. A method according to claim 1, wherein saidraw fabric is supplied to the heat treatment process in a manner offorming a short loop.
 4. A method according to claim 3, wherein theinitial temperature of the heat treatment process is not higher than 70°C.
 5. A method according to claim 1, wherein said raw fabric contains 5to 35 weight % of a low-melting fiber.
 6. A method according to claim 1,wherein said fabric is a woven fabric having a void percentage of atleast 50% in the condition of loading weight of 1500 g to 5 cm width ofsaid fabric in each of the longitudinal direction and the lateraldirection, said percentage of void being indicated by the followingequation: ##EQU6## wherein N is English count converted to single fiber,S is density of the spun yarn (g/cm²) and P is punching density perinch.
 7. A method according to claim 6, wherein said void percentage iswithin the range of 53 to 72%.
 8. A two-way stretch fabric producedaccording to the method of claim 1.